DAIRY FARMING DAIRYING. 725 



sufficient to give the fat .iilobules an albuiiiiiious coating-, after wliicli it 

 is heated, aerated without agitation, /. c, without churning, and sub- 

 mitted to alcoholic fermentation. The fermentation changes the char- 

 acter of the cream and entirely destroys its viscosity. The fat globules 

 rise to the surface and the other solids remain at the bottom, ^o 

 churning is required. The fat layer is separated and washed with 

 water to remove adhering particles of casein. 



The centrifugal separation of casein and insoluble phosphates 

 from milk, S. M. Babcock ( Wisconsin Sta. Ept:i895,pp. 93-99). — The 

 author mentions the difficulty of separating casein from the other con- 

 stituents of milk for the purpose of study, and refers to the variety of 

 theories that have been held in regard to its properties and the form in 

 which it exists iu the milk. 



"Formerly supposed to be in perfect solution, and afterwards to have soluble and 

 insoluble niodilications, both of which occur in normal milk, it is now generally 

 believed to be in large part and possibly wholly insoluble and suspended in a very 

 finely divided condition, which gives it a gelatinous or colloidal character." 



The author attempted to separate the casein from skim milk by means 

 of a centrifugal separator and thus obtain it in its natural condition. 

 Two experiments were made with an old-style Danish Weston sepa- 

 rator "arranged for the experiment by drilling a number of holes through 

 the skimming plate so that portions of the liquid nearest the center of 

 the bowl could be removed from time to time with the skimming tube 

 without disturbing the portion near the walls." The separator was run 

 at the rate of about 4,000 revolutions per minute. In the first experi- 

 ment the machine was stopped at the end of .S hours when the sides of 

 the bowl were found to be covered with a rather firm jelly-like deposit 

 about ^ in. thick, which was carefully removed. 



"This deposit was white with a peculiar fluoresence, being yellowish green by 

 transmitted light and having a bluish tinge by redected light. Wlieu shaken with 

 water it was easily diffused, forming a homogeneous white liquid resembling milk, 

 and no apparent separation took place when the ]i(iuid was allowed to stand ([uietly 

 for a considerable time.'' 



Various reactions showed the dej^osit to consist in part at least of 

 casein. It contained 29.67 per cent of solids, 22.10 per cent of protein, 

 and 2.98 per cent of ash. The ash was found to consist chiefly of phos- 

 phoric acid and lime, the results of 2 separate trials with different milks 

 showing 44.02 and 45.82 per cent of phosphoric acid and 43.72 and 45.30 

 per cent of calcium oxid, respectively. 



" This is api)roximately the same relation between lime and phosphoric acid found 

 in tricalcium phosphate and there is little doubt that the insoluble ash of milk 

 consists of this salt mixed with a little phosphate of magnesia.' 



To determine whether this ash was an integral part of the casein or 

 existed indei^eudently of it in the milk, skim milk diluted with water, 

 and pasteurized to prevent its souring, was treated in the separator 

 for 3 hours; it was then pasteurized again, kept in a refrigerator until 



